In recent years, many users in various layers such as students, house wives, employed persons, etc., use the Web (World Wide Web) to study about things thought in daily life and a way of thinking about things, or to exchange information in various fields with other users. Because of a large number of users use the Web, there is a case where a market study is performed by using the Web to use the result of the market study in developing a commercial product.
In order to extract users as investigation targets, a technique is suggested to extract users whose information contains a condition for search in a user attribute and search log. Also suggested is a technique to calculate a degree indicating superiority in the analysis by using numerical information regarding a contribution activity of a user.
The following patent documents disclose a background art.
Patent Document 1: Japanese Laid-Open Patent Application No. 2010-108119
Patent Document 2: Japanese Laid-Open Patent Application No. 2012-216168
The blog (Web Blog) is an example where users of the Web open their opinions to public. There may be a case where the contents of the blog on the Web are used for the investigation for products development. In the investigation for products development, a population is created by sampling an appropriate number of persons for each predetermined attribute to grasp an actual condition of each user as a consumer or customer by analyzing the blog of each user belonging to the created population.
The attribute of each user in the population changes with passage of time such that, for example, changing from a student to an employed person. Additionally, there may be a case where a user stops updating the blog or ends the blog itself.
On the other hand, in a case of surveying a product market, an accurate comparison with a past 20 survey result cannot be made unless an attribute ratio is maintained constant. Accordingly, in order to correspond to the above-mentioned change, a user whose attribute has been changed is omitted from the population to maintain the attribute rate in the population constant, and a new user having the same attribute is added to the population.
However, if the above-mentioned conventional technique is used, which effectively extracts users when investigation is made, it is difficult to maintain an attribute ratio in the population at a fixed value in response to the changes in the user attribute with passage of time.
Accordingly, it is desirous to create a population of investigation targets by considering an attribute ratio in the population ratio.